<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
  </head>
  <body>
    <div id="app">
      <input type="text" v-model.trim="username"  @keyup.enter="add"/><button @click="add">添加</button>
      <ul>
        <li v-for="item in list">{{ item }}</li>
      </ul>
    </div>

    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>

    <script>
      const app = new Vue({
        el: "#app",
        data: {
          username: "",
          list: ["篮球", "足球"],
        },
        methods: {
            add(){
                this.list.unshift(this.username)
            }
        },
      });
    </script>
  </body>
</html>
